Abstract: This study is to design an integrated heat recovery and air conditioner system and to investigate the feasibility and the potential performance of this system in changing conditions. Different season conditions and operating modes are studied based on the items of one hotel. In winter, heat recovered from wastewater is used on water heating and air condition and the surplus energy of air conditioner system is used on hot water system in summer. Dynamic energy simulation was performed with a comprehensive Domestic Hot Water (DHW) heating and air conditioning system composed of some components like High Temperature Heat Pump (HTHP) unit, water tanks, heat exchangers and pumps.